Police on Tuesday renewed the search for Madeleine McCann, the British child who disappeared in 2007, with officers digging and scraping the surface of land near a dam close to where she went missing in southern Portugal.

About 20 officers with rakes and hoe-like tools spread out in a line and began poking and raking the soil close to the Arade dam, which is located about 30 miles from the resort of Praia da Luz, where the 3-year-old girl was last seen 16 years ago.

Earlier, a couple of firefighters could be seen in a dinghy on the reservoir.

There were no immediate details on what progress was being made in the search.

The operation, headed by Portuguese police aided by German and British colleagues, was announced Monday. Portuguese officials said it followed a request from German authorities.

Portuguese police on Monday had set up two blue tents and cordoned off the area to the media and public. More than a dozen cars and police vans arrived early Tuesday.

Between 20 and 30 officers, some in uniform, were in the area. Witnesses said that police began searching shortly before 8 a.m.

Portuguese media say this is the fourth search for McCann, following the initial one in 2007 in the Algarve area and further efforts in 2013 and 2014. Another search was held in Germany in 2020.

This search is believed to be the first in the area of the dam.

In mid-2020, German officials said that a 45-year-old German citizen, identified by media as Christian Brueckner, who was in the Algarve in 2007, was a suspect in the case. Brueckner has denied any involvement.

Brueckner is currently serving a seven-year prison sentence in Germany for a rape he committed in Portugal in 2005.

He is under investigation on suspicion of murder in the McCann case but hasn’t been charged. He spent many years in Portugal, including in Praia da Luz, around the time of Madeleine’s disappearance.

German prosecutors in Braunschweig said in a written statement Tuesday that “criminal procedural measures are currently taking place in Portugal as part of the investigation into the Madeleine McCann case.”

They added that “the measures are being implemented by way of mutual legal assistance by the Portuguese prosecution authorities with the support of officers from the Federal Criminal Police Office.”

“More detailed information on the background is not being released at this time for investigative tactical reasons,” the statement said.

The case of Madeleine McCann stirred worldwide interest for several years, with reports of sightings of her stretching as far away as Australia, along with a slew of books and television documentaries about the case.

Rewards for finding Madeleine, who would now be 20, reached several million dollars.

British, Portuguese and German police are still piecing together what happened on the night when the toddler disappeared from her bed in the southern Portuguese resort on May 3, 2007. She was in the same room as her twin brother and sister, who were 2 at the time, while her parents had dinner with friends at a nearby restaurant.

Referring to the latest searches, Braunschweig prosecutor Christian Wolters said Tuesday that “we are investigating there in Portugal on the basis of certain tips,” but he declined to give further details.

Wolters said the search would “take a little time.” Portuguese officials said that the search would take place over the next few days.

Madeleine’s parents are not commenting due to the active investigation, according to an email response from the website set up for the search for the child, findmadeleine.com.